If the $X(3872)$ is a weakly bound charm-meson molecule, it can be produced in $e^{+}{e}^{-}$ annihilation by the creation of $D^{*0}{\overline{D}}^{*0}$ from a virtual photon followed by the rescattering of the charm-meson pair into $X$ and a photon. A triangle singularity produces a narrow peak in the cross section for $e^{+}{e}^{-}\to X\gamma$ about 2.2 MeV above the $D^{*0}{\overline{D}}^{*0}$ threshold. We predict the normalized cross section in the region near the peak. The peak from the triangle singularity may be observable by the BESIII detector.

• Received 3 May 2019

DOI:https://doi.org/10.1103/PhysRevD.100.031501

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Published by the American Physical Society